If you could go back in time and change just one thing, what would it be?

I would go back to save my family...but I believe that everything happened for a reason instead of wondering about what could have happened if I did that and that and why I did that just regretting stuff the whole time l carry my regrets stand then keep walking while putting a smile on my face believing that tomorrow is another chance and today is the way to that door i just live the moment bc now is now and this moment will never come back thinking positively about the future not because I'm scared to fight against my negativity I just chose happiness over sadness (and I dunno what I'm saying 😂😂😂)